Pneumatic tires are generally required to exhibit high performance in a manner that simultaneously meets multiple performance requirements. For example, in the case of a tire member such as a tread, in addition to requirements for abrasion resistance, cut resistance, low heat generation, and so forth, there is also demand for improvement of fatigue cracking resistance.
In one example of a conventional technique for improving fatigue cracking resistance, carbon black in which the degree of connection between particles of the carbon black is small (low structure carbon black) is compounded into a rubber composition.
However, a rubber composition containing low structure carbon black tends to suffer from poorer low heat generation and reduced cut resistance.
Examples of techniques for improving fatigue cracking resistance without using low structure carbon black include methods in which other physical properties of carbon black are adjusted. For example, PTL 1 discloses a rubber composition in which high structure carbon black having a CTAB value, a DBP value, and/or a 24M4DBP value in prescribed ranges is compounded with a rubber component that includes natural rubber and polybutadiene rubber blended in a specific ratio.